Let me add to that, anytime a terrorist is apprehended, follow the trail. Get phone records while you are at it.
I am not talking about this from strictly a US courts approach either. This is international.
No need for that in the case of the US. We've been listening to these calls all along, ever since we convinced Bin Laden that they were untraceable and un-interceptable.
In fact his son referred to his father having "no longer traceable Satellite Phones" back in 2003. When predator drones showed up Bin Ladin learned that the phones were indeed traceable and tap-able.
But India may not (yet) have this capability. With the increased cooperation between India and the US, you can bet this will change.